Band 3中四學生馮信希, 是出名的典型廢青、脾氣暴燥，品學包尾。一天，信希在校內闖下彌天大禍，校長願給他最後機會，要他參加「熱血合唱團試驗計劃」，以三間Band 3學校的學生組成的古典音樂合唱團，特訓九個月後參加「校際合唱團比賽」。信希毫無選擇只好勉強應承。
外界視這次計劃是比登天更難的任務，更恥笑他們是「爛橙合唱團」。但誰也意料不到美國著名華籍指揮家，曾消聲匿跡一段時間，有音樂界鐵血教官之稱的嚴梓朗 (嚴sir) 竟願來港作他們的指揮。
Hay, F.4 student from a Band 3 secondary school, is a typical decadent, cranky teenager. He once messes up big time in school, the principal offers Hay one last chance: to join an experimental Choir project named "Find Your Voice", or else he will be kicked out from the school.
Just like Hay, the members of the Choir are students come from 3 different band 3 secondary schools. The choir will compete in the Inter-school singing contest after going through a 9-months boot camp. Hay has no choice but to sing.
Everyone thinks the project is a mission impossible and even call the teens “Wretch” Choir. Whereas the sudden arrival of Mr. Yim, a prominent American Chinese conductor, turns the table. Yim, vanished from the world for a whole year and re-appeared completely out of the blue, agrees to be the conductor of the Choir.
Behind every face there is a story. Every Choir will sing its own music of life. When these 33 outcasts meet the strictest drillmaster, through life on life interaction, sweat and tears, what ensemble shall be expected from them?
Facing the billows of life, how will Yim and "Find Your Voice" surmount all difficulties to complete the mission and stride onto the stage with their head up high, to sing the most resounding voice with fervency, with love.